New up-to-date notebook on ODEs (from prev work) (pymc-devs#478)

* New notebook on ODEs drawing from the previously scatter work and updating based on the current state of the pymc examples

* Revision pymc-devs#1 ODE Notebook based on Pymcdev comments

* Revision pymc-devs#2 ODE Notebook changes based on comments

* Revision pymc-devs#3 based on comments

* Revision pymc-devs#5 based on comments

Author: gbrunkhorst